Stellar progenitors of black holes: insights from optical and infrared observations

TL;DR

This paper reviews optical and infrared observations to identify the mass limits of stellar progenitors that do not produce luminous supernovae, suggesting many massive stars end as black holes, especially in binaries.

Contribution

It synthesizes observational evidence across multiple methods to constrain stellar progenitor masses and links these findings to black hole formation in binaries.

Findings

Progenitors above 16-18 solar masses are rarely observed in supernovae.

Massive stars can quietly disappear without bright supernovae.

Stars >20 solar masses often do not show expected nucleosynthetic signatures.

Abstract

Here are reviewed the insights from observations at optical and infrared wavelengths for low mass limits above which stars do not seem to end as luminous supernovae. These insights are: (1) the absence in archived images of nearby galaxies of stellar progenitors of core-collapse supernovae above 16-18 solar masses, (2) the identification of luminous-massive stars that quietly disappear without optically bright supernovae, (3) the absence in the nebular spectra of supernovae of type II-P of the nucleosynthetic products expected from progenitors above 20 solar masses, (4) the absence in color magnitude diagrams of stars in the environment of historic core-collapse supernovae of stars with >20 solar masses. From the results in these different areas of observational astrophysics, and the recently confirmed dependence of black hole formation on metallicity and redshift of progenitors, it is concluded that a large fraction of massive stellar binaries in the universe end as binary black holes.